Disruption of the neural response to rapid acoustic stimuli in dyslexia: Evidence from functional MRI

Temple, Elise; Poldrack, Russell A.; Protopapas, Athanassios; Nagarajan, Srikantan S.; Salz, Talya; Tallal, Paula; Merzenich, Michael M.; Gabrieli, John D. E.

doi:10.1073/pnas.240461697

Cited by 216 publications

(161 citation statements)

References 46 publications

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“…47,48 Figure 3 shows the correct answers in each ear for gap intervals of 2 to 8ms. The percentage of correct answers for these gap intervals are similar in both ears; there was no higher prevalence of correct answers in any one ear.…”

Section: Resultsmentioning

confidence: 99%

Estudo da vantagem da orelha direita em teste de detecção de gap

Samelli

Schochat²

2008

Rev. Bras. Otorrinolaringol.

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Temporal resolution hearing skills are based on the minimum time necessary to segregate or solve acoustic events. This skill is fundamental for speech comprehension and can be assessed by gap detection tests. Some studies point to a right ear advantage over the left ear in temporal resolution tasks, since there is a preferential role of the left hemisphere in analyzing the temporal aspects of the acoustic stimulus. Aim: determine if there are response differences (gap detection thresholds and percentage of correct answers) between right and left ears in a gap detection test. Study: experimental. Materials and Methods: the gap detection test was applied to 100 adult individuals, after carrying out other audiologic tests in order to rule out possible hearing and/or auditory processing disorders. Results: We observed gap detection thresholds and average correct answers percentages, which were similar for both ears, regardless of which ear started the test. Conclusion: There was no ear advantage in the gap detection task.

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Section: Resultsmentioning

confidence: 99%

Estudo da vantagem da orelha direita em teste de detecção de gap

Samelli

Schochat²

2008

Rev. Bras. Otorrinolaringol.

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“…In human populations, fundamental deficits in cortical temporal processing affect general hearing and underlie poor language and reading skills (2,(27)(28)(29)(30)(31)(32). In babies, such deficits strongly predict older-age deficits in language and reading abilities (3,33).…”

Section: Discussionmentioning

confidence: 99%

Enduring effects of early structured noise exposure on temporal modulation in the primary auditory cortex

Zhou

Merzenich

2008

Proc. Natl. Acad. Sci. U.S.A.

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Studies have shown that acoustic experiences significantly contribute to the functional shaping of the structural organization and signal processing capacities of the mammalian auditory system during postnatal development. Here, we show how an early epoch of exposure to structured noise influences temporal processing in the rat primary auditory cortex documented immediately after exposure and again in adulthood. Pups were continuously exposed to broadband-pulsed noise across the critical period for auditory system development. Immediately after cessation of exposure at postnatal day Ϸ35 (P35) or Ϸ55 days later (i.e., P90) in other rats, the temporal modulation-transfer functions of cortical neurons were documented. We found that pulsed noise exposure at a low modulation rate significantly decreased cortical responses to repetitive stimuli presented across a range of higher modulation rates. The highest temporal rate at which temporal modulationtransfer function was at half of its maximum was reduced when compared with naïve rats. Low-rate pulsed noise exposure also decreased cortical response synchronization at higher stimulus rates, as shown by vector strength and Rayleigh statistic measures. These postexposure changes endured into adulthood. These findings bear significant implications for the role of early sound experiences as contributors to the ontogeny of human auditory and language-related abilities and impairments.cortical plasticity ͉ critical period ͉ temporal modulation-transfer function ͉ temporal processing S ounds in natural environments, such as animal vocalizations and human speech, have complex temporal structures. The importance of temporal structure in acoustic communication and orientation has been demonstrated in many behavioral, psychological, and neurophysiological studies. The auditory cortex plays a critical role in the perception of time-varying features of aural speech and of other complex acoustic stimuli. In humans, speech comprehension is correlated with responses of cortical neurons to temporal envelopes of speech (1), and individuals with impaired language abilities have impaired successive signal evoked cortical responses (2, 3).Earlier studies in different subprimate animal species have shown that cortical neurons display different temporal filtering properties (e.g., low-pass, responding to sound trains below certain rates, or band-pass, responding best to a specific rate, etc.) (4-7). In general, cortical neurons respond to repetitive sounds at far lower rates and with poorer temporal precision when compared with auditory nerve fibers or neurons in subcortical auditory nuclei and, in most mammalian species, are not able to follow individual sound presented at rates faster than Ϸ20 pulses per second (pps). It has been argued that for those more rapidly occurring stimuli (e.g., stimuli with repetition rate Ͼ100 pps), cortical neurons might apply a rate code instead of a temporal code (stimulus-synchronized responses) to represent the temporal structure (7). Most natural sounds, ...

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“…There is much evidence indicating that the left AC is specialized for processing rapidly changing sounds, regardless of whether speech or nonspeech (10)(11)(12)(13). In support of a causal connection to speech processing, there are a number of studies showing temporal processing deficits in language-impaired children (14,15) or dyslexic adults (16,17), and some of these studies indicate that these deficits can be overcome by training (14,17). Corresponding to the genetic basis of speech and language (18), brain imaging studies showed that in infants a few months old (19) and even in neonates (20), i.e., well before the onset of speech production, there is a left-hemisphere superiority to process specific properties of speech.…”

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confidence: 99%

Global versus local processing of frequency-modulated tones in gerbils: An animal model of lateralized auditory cortex functions

Wetzel

Ohl

Scheich

2008

Proc. Natl. Acad. Sci. U.S.A.

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Hemispheric asymmetries of speech and music processing might arise from more basic specializations of left and right auditory cortex (AC). It is not clear, however, whether such asymmetries are unique to humans, i.e., consequences of speech and music, or whether comparable lateralized AC functions exist in nonhuman animals, as evolutionary precursors. Here, we investigated the cortical lateralization of perception of linearly frequency-modulated (FM) tones in gerbils, a rodent species with human-like lowfrequency hearing. Using a footshock-reinforced shuttle-box avoidance go/no-go procedure in a total of 178 gerbils, we found that (i) the discrimination of direction of continuous FM (rising versus falling sweeps, 250-ms duration) was impaired by right but not left AC lesions; (ii) the discrimination of direction of segmented FM (50-ms segments, 50-ms silent gaps, total duration 250 ms) was impaired by bilateral but not unilateral AC lesions; (iii) the discrimination of gap durations (10 -30 ms) in segmented FM was impaired by left but not right AC lesions. AC lesions before and after training resulted in similar effects. Together, these experiments suggest that right and left AC, even in rodents, use different strategies in analyzing FM stimuli. Thus, the right AC, by using global cues, determines the direction of continuous and segmented FM but cannot discriminate gap durations. The left AC, by using local cues, discriminates gap durations and determines FM direction only when additional segmental information is available.asymmetry ͉ lateralization ͉ rodents

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Disruption of the neural response to rapid acoustic stimuli in dyslexia: Evidence from functional MRI

Cited by 216 publications

References 46 publications

Estudo da vantagem da orelha direita em teste de detecção de gap

Estudo da vantagem da orelha direita em teste de detecção de gap

Enduring effects of early structured noise exposure on temporal modulation in the primary auditory cortex

Global versus local processing of frequency-modulated tones in gerbils: An animal model of lateralized auditory cortex functions

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